Single armed microcantilevers have been used for sensing purposes in different devices. For example, scanning probe microscopes (SPMs) are a series of these devices that benefit from micro-probes. In SPMs typically, a microcantilever is moved over the surface of the sample, taps on the sample at a high frequency, or applies a miniscule force on a certain part of the sample. Conventional application of the SPMs is to produce topography of surfaces of different samples. With some modifications in elements of the SPM, it can also be used for measurements in materials with specific magnetic or electrical properties. Other examples include biological applications of SPMs for study of DNA and RNA, and investigation of structure and formation of carbon nanotube-based units.
Atomic force microscopes (AFMs) are a well-known and frequently used type of SPMs. AFMs were initially built for generating three-dimensional (3D) images from surfaces in nano-scale. FIG. 1 illustrates a schematic representation of different elements of an AFM. The stage holding the sample is moved upwards, until the microcantilever and the sample are engaged. Next, the piezoelectric stage moves in a planar motion to scan the considered surface. The reflected laser beam from the tip of the cantilever provides the required feedback of the sample surface topography. Different research has been conducted in this field. For example, methods for scanning the topography of a heterogeneous surface using AFMs have been proposed and utilized. In addition to common imaging application of the AFM, it has been used to measure mechanical properties of different materials and as a bio-sensor. Its ability to work in liquid environment makes the AFM an important tool for studying and even modifying biological samples. AFMs have been also used for nano-manipulation, where a nano-scale object on a sample is deformed or displaced.
Although AFMs were initially designed for generating images from surfaces in nano-scale, they have been used to manipulate and modify objects. Tip radius of less than 10 nm in the microcantilever probe accompanied with a stage which can move in nano-precision has made the AFM a suitable tool for different micro- and nano-machining applications. In particular, a microcantilever with a sharp tip is the cutting tool. The sample is placed on a piezoelectric-tube stage under the microcantilever. The stage pushes the sample into the microcantilever tip and then moves the sample so the tip plows the sample. For example, dynamic plowing lithography is a set of direct machining processes in which the microcantilever tip is vibrated at its resonant or higher frequencies using the piezo-stage under the sample, while the mechanical plowing is being performed.
However, the vibration amplitude is not accurately controllable using the piezoelectric stage in current machining works, which results in an inability to control the depth of the groove. As a result, the outcome of the process becomes less predictable, and the system cannot produce the desired shape and form of the channel or required object. In addition, the machining tool must penetrate into the sample, which eliminates the chance of fine machining in order of micron or submicron.
Among different nano-lithography approaches using the AFM, direct mechanical scratching is one of the simplest and most practical methods to cut a furrow, or even create 3D nano-scale objects. In the plowing process, the tip of the microcantilever is pressed into the sample, and using the motion of the stage, the desired groove is created on the surface. Ideally, the normal force would be kept constant to create a homogeneous groove by using the feedback provided by a reflected laser beam from the tip of the microcantilever.
Piezoelectric materials have been used in conventional one-armed microcantilevers of SPMs both for sensing and actuation applications. For sensing purposes, a layer of piezoelectric material, which is usually zinc oxide (ZnO) or lead zirconate titanate (PZT) is deposited on one side of the microcantilever. The piezoelectric microcantilever has been used in bio-sensing and chemical sensing for force microscopy, in addition to surface scanning and imaging of different samples in SPMs. When piezoelectric microcantilevers are used as actuators, they offer a much larger actuation bandwidth than that of conventional piezotubes. Piezoelectric microcantilevers can be excited in high frequencies to conduct the desired task. Due to the fact that the excitation input is applied directly to the microcantilever from the piezoelectric layer rather than by an interaction force at the tip or base excitation in conventional methods, they are more controllable and respond more quickly. However, piezoelectric microcantilevers have not been used in nano-machining processes.
Thus, there is a need in the art for an improved microcantilever device.